Educational gear cutting

thingiverse

Educational gear cutting is done using virtual milling with a virtual tool. Instead of creating gears directly in CAD programs by extruding calculated formulas, this project uses Lua to create an involute gear through several steps. A raw cylinder is prepared for milling, but it's not rendered by default and is colored red. Then, the milling tool - a trapezoid - is prepared in three different forms: as a 'raw' tool, a shifted tool, and a complex tool. The raw tool would be very thin if used alone, so it's moved perpendicular to the cylinder to cut two tooth flanks at once. These flanks have the same shape as the tool, meaning they're straight. The cylinder is also rotated slowly in one direction while the tool moves along its tangent in the same direction, changing one tooth flank and giving it an involute shape. In this program, I've taken a different approach to simplify teeth creation by using the raw tool with the same width as the gear, eliminating the need for perpendicular movement. A 'shifted' tool is then created based on the raw tool by adding shifted and rotated samples of the raw tool, similar to how it would be moved along the cylinder's tangent while rotating the cylinder. Using this 'shifted' tool allows two tooth flanks to be cut with a single operation without needing to rotate the cylinder. The slider 'Shift in %' makes it possible to change the shift in real-time and see its effect on the 'shifted' tool and the resulting gear. Next, the 'shifted' tool is cloned several times into a 'complex' tool that's used to cut all teeth at once, completing the gear. The source code offers options to tweak helical, herringbone, or arc tooth forms - feel free to play with it and have fun! References can be found below: Source for IceSL: https://members.loria.fr/Sylvain.Lefebvre/icesl/ One of its biggest advantages over OpenSCAD is real-time rendering, but this also makes it less compatible due to its requirement for a modern graphics card. A WebGL-based version is available, but I recommend against using it with this complex script because of the slow JavaScript and WebGL overhead. Scripting documentation for IceSL: https://gforge.inria.fr/plugins/mediawiki/wiki/icesl/index.php/Scripting Lua can be found at https://www.lua.org/. Tested graphic cards include: GeForce GTX 480 / 580 / 680 / 970 / Titan GeForce GT 555M Intel HD 4400, 4600 AMD Radeon 290X (with limitations)